It is conventional for many state-of-the-art cathode ray tubes, such as those employed in color television applications, to have small neck diameters and integrally size-related closure portions. The plurality of connective leads or pins protruding from the closure are usually oriented in a pin-circle array evidencing rather close inter-lead spacings because of the restrictive circumferential arrangement. Since high voltage differentials are existent between certain of the leads, it has been conventional practice to insulate the leads in the base, especially the high voltage ones, by surrounding them with a viscous dielectric material introduced into the base when such is positioned on the closure portion of the tube.
A common procedure for introducing the dielectric material into the base is by pressurized application through the terminal aperture in the substantially axially-oriented hollow crown of the base, that part which spatially encompasses and protects the sealed exhaust tubulation of the tube. The pressurized injection of the dielectric forces it inwardly through the space between the tubulation and the internal wall of the crown to the wafer or flange region of the base. There it is intended to flow around the leads, the high voltage ones in particular, to effect electrical insulation therearound.
Because of minute lead positioning deviations inherent in stem manufacturing, it has been a practice to incorporate pin circle tolerances in the base by slightly increasing the diameter of certain apertures in the base wafer or flange, usually those diametrically opposed to the high voltage lead-receiving apertures. While the incorporation of this lead tolerance feature in the base minimizes possible binding when assembling the base to the tube, there are occasions when a problem is evidenced. In endeavoring to achieve desired encompassment of the high voltage leads with the dielectric material, the pressurized dielectric is sometimes squeezed out along the pins in the substantially opposed larger-sized apertures.